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B. J. MALLETT, Jr.

BOILER OR OTHER FURNACE. No. 258,450. Patented May 23, 1882.

IN V E [V T0 l'dowwrdJJ/alleilj:

By his Afforney N, PETERS. Phuwumo n hcr. Washington. 6.11

NITED STATES PATENT OFFICE.

EDWARD J. MALLETT, JR, OF NEW YORK, N. Y.

BOILER OR OTHER FURNACE.

SPECIFICATION forming part of Letters Patent No. 258,450, dated May 23, 1882.

Application filed January 31, 1882.

To all whom it may concern Beitknown that I, EDWARD J. MALLETT,J1., of the city, county, and State of New York, have invented a certain new and useful Improvement in Boiler and other Furnaces, of which the following is a specification.

My present improvement is the outgrowth of the system for promoting the combustion of fuel in boiler and other furnaces set forth and illustrated in pending applications in my name for Letters Patent of the United States, and it is particularly adapted to the needs of that system.

To cause the burning of carbonic-oxide and other combustible gases generated from fuel burning in a furnace, hot air not only must come in contact with these gases, but must be thoroughly and rapidly mixed with them before their great velocity carries them to cooler portions of the furnace. To effect this mixture of gases with air, hot air can be let into the furnace, above the grate-bars, through ducts or passages opening into the furnace through or behind the bridge-wall, and for this purpose I prefer to use hollow grate-bars.

Hitherto when hot or cold air has been allowed to enter the furnace it has been brought in without regard to any method of definitely compelling the fuel-gases and the air to be brought into intimate contact. For example, in a boiler-furnace in which the fire is bounded at the rear by the ordinary bridge-wall the gases evolved from the fuel on the grate, being in a highly heated condition, rise rapidly against the boiler and flow along the curved faces of the boiler and the brick side walls of the furnace. If these gases passing over a brid ge-wall are thus allowed to instantaneously rise and impinge upon the colder surface of the boiler, they get out of reach of any air which may be caused to enter the furnace for the purpose of effecting their combustion, because, being very much hotter than any hot air that enters, the gases tend to leap up and occupy the higher spaces of the furnace along each side of the boiler. The colder surface of the boiler also exerts a cooling action on these as yet unignited inflammable gases; but before they can descend to lower strata occupied by the cooler air their great velocity has swept them up the chimney, through the tubes or flues of the boiler,

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in an unburned condition. It is to this cause, among others, that I attribute'the fact that hitherto even the introduction of hot air in jets into furnace-gases has never accomplished, so far as I am aware, their complete combustion.

In order to prevent the ascension of hot furnace-gases into the higher and cooler furnacespace before they are completely mixed with air introduced into the furnace for the purpose of burning them, my improvement has been devised; and to this end I make use of a septum or division-wall at the rear of or beyond the fire-box, which is carried up completely to the bottom of the boiler, and completely shuts off the passage of the fuel-gases from the firebox to the chimney or discharge flue, except through an opening or openings made specially in the division-wall for that purpose. This solid division-wall prevents the gases from being urged upward, and permits them to escape only through the specially-provided opening or openings therein. In conjunction with this septum or division-wall I use channels or conduits through which hot air is introduced and discharged into the furnace at the point where the gases pass through or out beyond the division-wall, and they are thus brought into immediate and intimate contact with the air. I use in connection with these appliances a suction-fan or air-exhauster, which draws air both\ through the ash-pit and through the hollow grate-bars or other hot-air channels, thus having a forced suction-draft. I also use in conjunction with the foregoing instrumentalities registers or gates by which the proportionate volumes of air drawn from these two sources can be regulated and varied at pleasure; and, finally, I employ in said combination, for the purpose of cooling the air before it reaches the fan, a condenser or cooler intermediate between the fan and the furnace.

The instrumentalities named in the para graph last above form the subjects-matter of my aforesaid pending applications, and are only claimed herein so far as they enter into combinations of which the perforated septum or division-wall and hot air ducts are elements.

The nature of my improvements will readily be understood by reference to the accompanying drawings, in which I have represented a boiler-furnace embodying my improvement in its preferred form. In this preferred embodiment of the improvement, tubular or hollow grate-bars are employed as the hotair-introdueing channels; and with the segtum and air-channels are combined the fan, registers, or gates and condenser hereinbefore referred to.

Figure 1 is a longitudinal central section, partly in elevation. Fig. 2 is a sectional front elevation.

The furnace has the usual fire-box, A, ash pit B, and boiler G, with the usual draft or discharge flue, 1), which leads to a suction-fan, E, driven bysuitable means. At the rear ofthe fire-box, and occupying the place usually occupied by the bridge-wall, is the septum or division-wall F,whichis a wallextending from side to side of the furnace,and built up around the boiler, so as to constitute a solid partition. This septum, at about the height of the ordinary bridge-wall, is perforated, and through thispart only can the fuel-gases pass from the fire-box to the draft or discharge flue beyond. The perforation consists in the present instance of openings a. The openings thus far used by me, and which give excellent results, are each about two and one-half inches wide and six inches high, with their tops about eighteen inches below the lowest curve of the boiler, and are arranged in a horizontal row throughout the width of the septum, say at intervals apart oftwoand one-halfinches. I do not, however, restrict myself to any particular size, shape, or arrangement of the openings. There may, if desired, be formed inthe wall a continuous slit or slot.

The grate-surface is composed of tubular or hollow grate-bars I), open from end to end, and opening at the rear through the septum or division-wall, in proximity to the point at which the gases issue from the divisionwvall, so that the air drawn in through them will be discharged in heated condition into the furnace at a point where it will immediately mingle intimately with the fuel-gases. The front open ends of the tubular grate-bars are controlled by a register or gate, 0, and a similar register, d, controls the air-inlets vto the ash-pit, so that the proportionate volumes of air entering the furnace at these points can be varied at pleasure.

At a point between the furnace and the fan E there is a condenser, Gr, through which the heated air passes on its way from the furnace to the fan. This condenser is what 1 term a water-contact condenser, containing a water-supply pipe, which sprays water upon a bed or screen of coke or other suitable material through which the air is drawn. By its passage through the coke-screen, through which the watereonstantly trickles,theheated air is cooled.

Having described my improvement, I state my claim as follows l. The combination, with the fire-box, the draft-flue, and the suction-fan or air-exhauster, of the perforated septum 'or division-wall, and separate, distinct, and controllable air channels or ducts, admitting air in regulated quantities, the one to the ashpit, the other to the furnace, at a point where the air will meet and mingle with the fuel-gases passing through or issuing from the said division-wall, substantially as hereinbefore set forth.

2. The fire-box, the draft-flue, and the suction-fan or air-exhauster, in combination with the perforated septum or division-wall, the separate and distinct air channels or ducts, admitting air, the one to the ash-pit, the other to the furnace, at a point where the air will meet and mingle with the fuel-gases passing through or issuing from the said division-wall, and registers or gates for said airchannels, substantially as hereinbefore set forth.

3. The combination, with the air-exhauster and the condenser or cooler, of the furnace provided with perforated septum or divisionwall, and with separate and distinct sets of valve or register controlled air channels or ducts, substantially as and for the purposes hereinbefore set forth.

In testimony whereof I have hereunto set my hand this 24th day of January, 1882.

EDWARD J. HALLETT, (In.

\Vitnesses:

15.;A. DICK, M. BAILEY. 

